In the state of the art, analyzer systems for testing a device under test are known, wherein the analyzer systems comprise phase coherent sources and receivers. The phase coherence is established by an internal analyzer marker signal that controls the timing, particularly the one of the sources and the receivers.
Further, an analyzer source provides a continuous wave input signal to a comb generator of the analyzer system, wherein the continuous wave input signal serves as a clock signal for the comb generator. The comb generator generates an output signal, wherein the spectrum of the output signal can be used for calibration of phase in frequency converting measurements such as mixer measurements, non-linear component characterization or rather U/I-waveform reconstruction.
Important figures of merit of the spectrum of the output signal relate to the signal to noise ratio of the comb lines as well as a fine frequency spacing within the spectrum. Accordingly, pseudo random binary sequences (PRBS) or frequency divider sequences are typically used that allow to effectively reduce the frequency spacing of the comb lines and, in case of pseudo random binary sequences used, to increase the signal to noise ratio of the comb lines. However, the spectrum of the output signal, namely the one of the periodic output sequence, has a phase ambiguity precluding the system to be used for absolute phase calibration.
Accordingly, there is a need for a system that permits absolute phase calibration.